The present invention relates to a shaped article of a fluorine-containing synthetic resin having improved surface properties and a method for the preparation thereof. More particularly, the invention relates to a shaped article of a fluorine-containing synthetic resin having increased wettability, printability, susceptibility to adhesive bonding, moderate antistatic performance and the like improved surface properties and a method for the preparation of such an improved shaped article of a fluorine-containing synthetic resin by the method of treatment of the article with low temperature plasma produced in specific gaseous atmosphere.
As is well known, shaped articles of fluorine-containing synthetic resins, typically represented by polytetrafluoroethylene resins, are very excellent in general in their chemical stability and heat resistance as well as in their electric properties, very low coefficient of friction and weathering resistance. On the other hand, some of their unique surface properties cause several serious problems in the practical use of such shaped articles. Specifically, the surfaces of shaped articles of fluorine-containing synthetic resins have poor wettability with water, poor receptivity of printing inks, insusceptibility to adhesive bonding and extremely strong accumulation of static electricity to cause various disadvantages and inconveniences in the practical application of them so that their application field is narrowly limited.
With an object to solve the above described problems in the shaped articles of a fluorine-containing synthetic resin, several methods have been proposed in the prior art in which the surface of the shaped article is subjected to the treatment by electric corona discharge or to the exposure to an atmosphere of low temperature plasma of an inorganic gas to cause surface oxidation resulting in the improvements of the surface properties to some extent. These methods are, however, far from satisfactory because the improvement obtained thereby is insufficiently low and, moreover, the effect obtained by the above mentioned treatment has very poor durability and permanency.
On the other hand, several attempts have been made by the treatment with chemicals of graft-copolymerization on the surface by utilizing irradiation with actinic rays such as electron beams, ultraviolet light, gamma rays and the like in order to obtain improved surface properties of the shaped articles. These methods are, however, disadvantageous from the practical standpoint due to the complicated process involved in the method and difficulty in obtaining desired degree of improvement presumably due to the extreme chemical stability of the fluorine-containing synthetic resins.